Table 1: Significant overlap between Type 1 and Type 2 disease characteristics.
Review of the literature demonstrates that Type 1 and Type 2 patients have similar disease characteristics across multiple parameters, including frequency of certain symptomology (N = 130 Type 1, 23 Type 2, data taken from Brunetti-Pierri 2008), residual βgal activity (N = 89 Type 1, 55 Type 2), and age of first symptom onset (N = 109 Type 1, 61 Type 2) (Sinelli 2005, Santamaria 2006, Santamaria 2007, Caciotti 2007, Hofer 2010, Caciotti 2011, Bidchol 2015, Regier 2016, Feng 2018, Lee 2018).
| Type 1 | Type 2 | |
|---|---|---|
| Dysmorphic features | 87% | 66% |
| Hypotonia | 96% | 50% |
| Developmental delay / Mental retardation | 100% | 96% |
| Seizures | 9% | 18% |
| Cherry-red spot | 59% | 18% |
| Cardiomyopathy | 34% | 38% |
| Hepatosplenomegaly | 85% | 30% |
| Skeletal abnormalities | 82% | 69% |
| Extrapyramidal signs Observed in Type 3 | 0% | 0% |
| Dystonia Observed in Type 3 | 0% | 0% |
| Residual βgal activity | <1% to ~10% Assay-dependent |
<1% to ~25% Assay-dependent |
| Age of first symptom onset | Pre-birth to ~12 months | ~6 months to ~5 years |